b7100 hst gasket question

[rScotty]

I cleaned my whistle, and while I had the radiator off I cleaned all the cooling fins.

Good. Be sure to use no more than a 50/50 mix of ethylene glycol and water. If your climate is hot, use less glycol to the water. Either use a premix, or I used to buy a gallon of 100% ethylene glycol at the auto parts store and mix it with distilled water. You need to premix and shake it well before pouring it into the radiator. The reason for the distilled water is that you are also trying to keep the inside of the radiator and engine block as clean as possible from any kind of coating.

It's also important to keep a good seal between the radiator and fan shroud to make sure that the fan is pulling air through the fins rather than around from the side of the radiator.

Thermosiphon cooling works pretty well on the flat or going uphill. It suffers when working down slopes that are steep enough to put the radiator somewhat below the level of the engine. That's pretty steep and not usually a problem - especially since the engine is doing less work on a downhill slope. I did overheat mine once years ago when digging along a steep drainage ditch with the front loader. All alone and concentrating on the work.....the blast of steam through the whistle nearly caused me to soil my pants. Back on the level or pointing slightly uphill it cooled down quickly while idling...
rScotty

 

[omrebel]

We don't have many hills but I use it to mow straight down and back up my pond dam. It's pretty steep, I have to wear my seatbelt. I don't mow it all at once because it does run hot. I've always used 50/50 antifreeze/water though. It's a great mowing machine. After bending both my 10mm wrenches to get the right bend, I finally got the dynamo off. The gasket looks good-maybe it would be better to re-use? But I don't want to do it twice....

 

[rScotty]

We don't have many hills but I use it to mow straight down and back up my pond dam. It's pretty steep, I have to wear my seatbelt. I don't mow it all at once because it does run hot. I've always used 50/50 antifreeze/water though. It's a great mowing machine. After bending both my 10mm wrenches to get the right bend, I finally got the dynamo off. The gasket looks good-maybe it would be better to re-use? But I don't want to do it twice....

If the gasket looks good it's probably the original,and came off nicely because it didn't have any goo on it. No reason why not to re-use it as you are going to build it up with the red silicone anyway. There's an art to re-using gaskets, but it isn't difficult. If you do re-use it, take care to apply the silicone in a nice even layer and let it go ahead and cure a little longer so it has a rubbery surface.

Another gasket trick for re-using gaskets is to clean the metal mating surfaces well and apply a thin layer of grease to the metal. Then if the silicon of the gasket is allowed to cure to rubbery before installing, the grease will help the rubber of the silicon to slide into any minute imperfections and also serve as a barrier to adhesion so that next time you take it apart the gasket will be usable again.

When re-using gaskets, it's the bolt holes that tend to wear out before the gasket face itself does.

rScotty

 

[rScotty]

We don't have many hills but I use it to mow straight down and back up my pond dam. It's pretty steep, I have to wear my seatbelt. I don't mow it all at once because it does run hot. I've always used 50/50 antifreeze/water though. It's a great mowing machine. After bending both my 10mm wrenches to get the right bend, I finally got the dynamo off. The gasket looks good-maybe it would be better to re-use? But I don't want to do it twice....

That's interesting about the heating up when mowing. Does it run hot when going downhill? That's when the thermosiphon is least efficient.

You can help it run cooler by slightly reducing the amount of glycol. The real technical recommended percentage was always 40% glycol to 60% water.... that gives a noticible increase in cooling over a 50/50 mix while still protecting down to about -13 F. We just always said 50/50 because it was easier to measure for most folks.

Resist the impulse to run straight water.... eventually everyone who does forgets to change it in the Fall and the result is a cracked block. That's a much bigger problem than just running hot in the summer. Thermosiphon engines are designed to run a bit hot without damage. Glad to hear yours is doing well. Not sure I'd change much. Those were dandy tractors. Well-designed for intelligent owner maintenance and given that they would last a lifetime.
rScotty

 

[omrebel]

I mow forward going down the dam and mow in reverse back up, no place to turn around at the bottom of most of it. It only gets dry enough to mow 2 or 3 times a year so it's pretty tough mowing. I think that it's working pretty hard is one reason it gets hot. Also the fan was in the way whenever I blew the radiator out, I didn't realize how dirty it was until I removed it. It's clean now and I think it'll cool better.

The gasket came cleanly from the dynamo but is still stuck to the engine side. I'm was thinking I may do more damage by scraping it off, and maybe I could put a thin layer of silicone on it, let it cure. I do have a new gasket if that's a bad idea.